Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort.
Level 3 - non-randomized controlled study
Prospective observational cohort study with 20-year follow-up
PubMed 26992108 · doi:10.1111/joim.12496
What was done
Researchers examined the association between sun exposure habits and main causes of death using a competing risk survival analysis in the Melanoma in Southern Sweden (MISS) prospective cohort. The study followed 29,518 Swedish women aged 25–64 years recruited between 1990 and 1992 over a 20-year follow-up period. Sun exposure habits and potential confounders were assessed from baseline questionnaire data.
What was found
Women with active sun exposure habits had lower rates of cardiovascular disease (CVD) and non-cancer/non-CVD death compared to women who avoided sun exposure. Because of longer survival, the relative proportion of cancer deaths increased in the high-exposure group. Nonsmokers who avoided sun exposure had a life expectancy similar to smokers with the highest sun exposure. Avoidance of sun exposure was associated with a reduction in life expectancy of 0.6 to 2.1 years compared to the highest sun exposure group.
Why it matters
This study suggests that sun avoidance is an independent risk factor for all-cause and cardiovascular mortality in northern European women, with an effect size on life expectancy comparable to smoking.
Limits
The study included only Swedish women, limiting generalizability to men, other geographic latitudes, and diverse skin phototypes. Exposure was based on baseline self-reports without longitudinal reassessment, and observational design leaves room for residual confounding from unmeasured lifestyle factors.
Cited by
- partial A large-scale study from Sweden found that greater sunlight exposure was associated with increased lifespan, with smokers who received more sunlight living longer on average than non-smokers who received less sunlight.